Starry cobalt-based electrode

D812: Hard core sealing expert for high temperature and high pressure valves

In the high-end industrial fields such as electric power, petrochemical, chemical industry and chemical fiber, equipment often needs to operate in extreme environments ofhigh temperature, high pressure and strong corrosion for along time. Ordinary steel and welding materials often fail rapidly under such conditions, resulting in equipment downtime and even safety accidents. D812 Co-base electrode(referred toas D812 electrode), as a high-performance Co-Cr-W alloy surfacing material, with its excellent high temperature wear resistance and excellent corrosion resistance, has become the preferred hard core material for repairing and strengthening key parts such as high temperature and high pressure valve sealing surface and high pressure pump sleeve.
This electrode uses advanced titanium calcium coating technology, made of continuous casting Stellite alloy core, designed for DC welding, can deposit high hardness, stable performance of the surfacing layer.

🔬Product core: Why choose quality D812?

The core competitiveness of QDE D812 lies in its ** high“ carbon high tungsten” cobalt alloy system **, which has significantly improved heat resistance and wear resistance compared to D802:
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Very high hardness and wear resistance (HRC 44): This is a significant label for this electrode *. D812 belongs to cobalt base alloy withhigh carbon and high tungsten,and its hardfacing hardness is as high asHRC 44-45. Compared to D802, it contains more carbon (C 1.0-1.7%) and tungsten (W 7.0-10.0%), which makes the carbide formed harder and has better resistance to intermetallic wear and abrasion, especially suitable for high stress wear conditions.
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Excellent high temperature resistance (* high 850℃): D812 surfacing metal with cobalt as the matrix, containing chromium 26-32%. This combination of ingredients gives it excellent high temperature stability. The hardfacing layer can maintain good wear resistance and corrosion resistance under650℃working environment, and even maintain high hardness and oxidation resistance under850℃high temperature.
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Excellent corrosion resistance and scratch resistance: due to the high proportion of chromium and cobalt, quality DE D812 has good corrosion resistance to weak acids, weak bases and high temperature and high pressure gases. At the same time, its high hardness characteristics make it have excellentanti-scratch abilityin the application of sealing surface, which can effectively prevent the valve from pulling the sealing surface during the opening and closing process.
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Good process adaptability: designed for ** DC reverse connection (DC+)**, high quality D812 arc combustion stability, uniform melting of the coating, good slag coverage, easy slag removal. The weld formation is beautiful and smooth, without obvious porosity or slag inclusion defects.

📊Technical parameters and chemical composition

In order to facilitate you to quickly understand the inherent quality of this product, we have compiled the following core parameter table:

performance index	Typical values/ranges	remark
product model	D812 (EDCoCr-B-03)	cobalt-based surfacing electrode
main component	C 1.0-1.7%, Cr 26.0-32.0%	W 7.0- 10.0%, Co balance
hardfacing hardness	HRC ≥ 44-45	ambient hardness
* High application temperature	650℃ - 850℃	Depending on specific conditions
power source type	Reverse DC connection (DC+)	recommend to use

🏭typical application scenarios

ZDE D812 cobalt-based electrode“” is active in the following core industrial fields by virtue of its dual characteristics of superhard + high temperature resistance:
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High temperature and high pressure valve sealing surface:
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It is specially used for surfacing welding and repairing sealing surfaces ofhigh-pressure gate valves,globe valves andcheck valves inpower stations, which is the core application field.
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Petrochemical equipment:
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Used forhigh pressure pump shaft sleeve,inner liner,hot shear blades and other parts subjected to high stress wear and corrosion.
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Chemical fiber and textile machinery:
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It is suitable for repairing and strengthening wearing parts suchas cutting edge andscrew push rodof chemical fiber equipment.
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Other wear parts:
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Forengine valves,turbine blades,hot dies and other high temperature wear resistance and anti-scratch occasions.

💡Welding process recommendations

In order to ensure that the quality of D812 electrode to play the best performance, avoid cracks and pores, it is recommended that you follow the following process points during construction:
1.& nbsp;
Electrode drying:
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Before welding, the electrode must be baked at about200℃ for more than1 hourto remove moisture from the coating and prevent porosity during welding.
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Workpiece cleaning:
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Before welding, theoil stain, rust, oxide scale and moistureon the surface of the workpiece must be thoroughly removed to expose the metallic luster.
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Preheating (critical):
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Depending on the size of the workpiece and the type of base metal, preheating at300-600 ° Cmust be carried out. For large workpieces or high restraint parts, the upper limit of preheating temperature should be taken to prevent the occurrence of cold cracks.
4.& nbsp;
Welding specification:
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Current selection:low current andshort arc welding are recommended. For example, the current of 4.0mm electrode is about 120- 160A. Small current short arc welding is suitable to reduce the penetration of base metal and reduce dilution rate.
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Operation method: Keep electrode vertical to work surface as far as possible, and adopt short arc operation.
5.& nbsp;
Post-weld slow cooling and heat treatment:
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After welding,slow cooling treatment shall be carried out immediately. It is recommended that the workpiece be placed in a dry and hot sandbox or straw ash for slow cooling, or that the work be immediately placed in a furnace at600-700 ° Cfor tempering for 1 hour and then slowly cooled. It is forbidden to quench (such as watering) to eliminate welding stress and prevent cracks.

📝sum up

Quality Stellite Co-base electrode D812is the golden key to solve high temperature and high pressure valve sealing surface wear, high stress wear failure and corrosion resistant parts repair problems. It provides solid industrial protection for you with its high hardness metallurgical structure and extremely high temperature stability.
If you are looking for a hardfacing solution that isresistant to high temperatures,corrosion,hardness andscratch, the Quality D812 is your trusted industrial partner.